If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.

Comment

is there a sure fire method of telling cast aluminum from pig iron or commonly called, white metal. to me, they look the same, thanks, kevin

Pig iron is the cast iron that gushes out the bottom of a blast furnace and cast into something that sort of looks like a lot of piglets feeding at their mothers you-know-whats. It then was thrown into the open-hearth or Bessemer converter to turn into steel. It's mostly been replaced by taking the molten Iron directly from the blast furnace to the oxygen converter in specially built, well insulated, railroad car (called a bottle car or a torpedo car)

You're probably trying to differentiate cast aluminum from "white metal" (aka pot metal) which is usually zinc plus some stuff. One differentiator is weight, zn is over twice as dense as al (7+ g/cc vs about 3g/cc). Zn is close to iron's density. If the thing your trying to classify feels about as heavy as it should if it was made of iron or steel, it's probably white metal, if much lighter, probably aluminum. Melting point is also very different (1220f for al vs about 800f for zn) --- can you try controlled melting of a bit?

If you do find a good, sure fire, fool proof, way, let us all know. I've had to do a few minor repairs of decorative cast doodads that could have been either al or zn. I ended up low-temp soldering it.

Frank

P.s. if you truly are trying to differentiate iron from white metal ... one will rust, the other won't :-)

Comment

sorry for mis speaking the term, pig iron, its been a long and hectic day, but you guys got my point any way, and thanks frank, that is very good info to keep in mind, the weight factor is probably the best clue. i thought at one time that the big buck car restorers were asking the welding industry to come up with a way of welding this stuff, you mentioned low temp solder, frank, can you go a bit further with that answer if you please, and has any one else been successful with repairs on this metal. thank you

Comment

i thought at one time that the big buck car restorers were asking the welding industry to come up with a way of welding this stuff, you mentioned low temp solder, frank, can you go a bit further with that answer if you please, and has any one else been successful with repairs on this metal. thank you

Aluminum is, of course, weldable. I assume you want to know what to do with pot/white metal?

What it was (if I remember right) was that a neighbor had some broken doodads made of Mystery Metal and asked if I could fix it. (After all, I have a welder, and metal is metal so I should be able to just weld it right up, right? :-) Since they weren't steel, I decided to try and solder the pieces (as far as I knew then and still know now, white/pot-metal is solderable). I bought a small Bernzomatic butane torch (not the normal propane torch, this one is much smaller, pinpoint flame, low heat volume ... current model is their ST-200 Microtorch) since they were fairly small and I didn't want to risk melting them. Also I got a selection of solders from the local hardware store ... nothing fancy, just whatever they had. One was a relatively low-temp one (it has a lot of Bismuth in it, if I remember right). I don't recall the brand/type/manufacturer/etc nor whether it was fluxcore or not.

Anyway, I cleaned the broken surfaces a bit --- just to get any pieces of goop off, and then soldered the two pieces together in the normal manner. It worked quite well.

Comment

White metal is weldable with O/A. We buy rods from the LWS for it. I believe they are just pure zinc. However as white metal ages it gets "rotten"--oxidized I expect. At that point recasting is the only reasonable option. As well if it has been chrome plated or otherwise plated, the plating must be removed from the weld area due to different melting points. I usually tell people if they can buy a replacement to just do that. I long ago got over the need for another challenge.
Meltedmetal

Comment

Pot metal, aka zinc based, die cast can be welded with TIG, on AC.
I've got a low temp (about 450˚F), higher temp (about 650˚F)
and at least one other type of rod.
There's a huge number of types of pot or die-cast zinc alloys.
Some weld okay, some don't.
Doing this takes some finesse with the torch and setup, since it's way too easy to create a molten puddle that ustah be the part-quickly. The part will give no warning that it's going to disappear.
Pot metal doesn't transfer or spread the heat out at all; which means the arc on time may be all of a second or two, before stopping, then cooling with air blow off.
The zinc want to flare, while one's dabbing the filler to get some semblance of a puddle that's bonding to the parent material. After cool down, then ss brush and go back at it-again.
It's time consuming.
Grinding or sanding can overheat the part, causing more problems unless doing intermittent cool downs.
It's worked okay for lasting repairs on stuff that takes the filler.
High stress things like door handles--forget about it.

Comment

i did try the tig on ac, i could not get a puddle to form, granted the part i was trying to repair was small in nature and the puddle would be in a confined area with support ribs cast all around the break, when i struck an arc, the arc just scattered all over the place, staying inside of the support ribs, the closest thing that i can compare that too is welding 7018 way hot on dc into multiple corners and getting major arc blow